The Mouse and Transplantation Core will have overall responsibilities for training all Projects in the transplantation of skin allografts and monitoring for graft survival. It will also have responsibility for maintenance, treatment, and surgical manipulation of virus treated experimental animals in BSL2/3 level biocontainment. All Program Project experiments will utilize VAF animals housed in a VAF facility or in a limited access biocontainment facility designed to maintain the highest degree of cleanliness. The emphasis on strict limited-access biocontainment will preclude cross-contamination and corruption of outcomes by unintended infectious agents. The objectives and responsibilities of the Animal Core Unit are as follows: By administering or training personnel in proper administration of reagents, including viruses, anti-CDI 54 mAb, other monoclonal antibodies, cells, TLR agonists, and other specific agents to be developed in the course of the Program to animals in VAF and in biocontainment. By preparing hematopoietic synchimeras, an animal model system that is crucial for the success of Projects 1-3. Procurement of cells, biopsy and autopsy specimens for histological and flow cytometric analysis from animals in biocontainment. Animal Core personnel will perform or assist with performing skin grafts for all Projects. Serological testing of experimental animals to document that infection has occurred and that there is no cross-contamination. In brief, the Mouse and Transplantation Core will provide essential assistance and personnel training to each Project with the management and execution of in vivo studies conducted in defined VAF facilities and in strictly controlled infectious conditions in biocontainment.